1. Field of the Invention
The present invention relates generally to telescoping slide assemblies. More particularly, the present invention relates to a slide assembly that occupies a reduced cross-sectional area while maintaining a high load rating, and being especially well-suited for use in 1U and 2U internet server mounting applications.
2. Description of the Related Art
The hardware components comprising a computer server, such as an internet server, for example, are arranged and secured within a metal or plastic enclosure, or chassis. The server/chassis assembly is then typically housed within an enclosed cabinet, often containing multiple servers arranged in a vertical manner. In one particularly advantageous arrangement, each chassis is mounted on a pair of telescoping slide assemblies so that the server may be easily withdrawn from the cabinet for inspection, repair or replacement. It is contemplated that 1U and 2U servers will comprise the majority of the future internet server market.
A large number of cabinets, each containing multiple computer servers, often covering thousands, or tens of thousands, of square feet of floor space may be found in a single location. Storage costs for computer servers are typically calculated on a basis of square feet of floor space occupied per server. Accordingly, it is highly desirable to reduce the area occupied by the cabinets, in order to maximize the number of cabinets, and thus servers, that may be stored in a given area.
One impediment to reducing cabinet dimensions has been the cross-sectional size of the available slide assemblies, or xe2x80x9cslidexe2x80x9d, for short. Additionally, in an effort to reduce design and purchasing costs, it is desirable to provide a single slide that is suitable for both the 1U and 2U server applications. Therefore, a need exists for a slide of reduced cross-sectional area that is structurally capable of supporting a vertical load produced by either a 1U or 2U internet server.
Additionally, in a computer server application, it is highly desirable to utilize an over-travel type slide assembly. An over-travel slide is capable of extending a greater distance than the length of any one of the individual slide segments. By utilizing an over-travel slide, the server may be completely withdrawn from the cabinet to permit access to the rearward end of the server where cables, such as power cables or networking cables, may be located. A common over-travel slide has three, or more, individual slide segments telescopingly engaged with one another. For example, in a three-segment slide assembly, an outer slide segment may be connected to the cabinet and an inner slide segment may be connected to the computer server chassis. An intermediate segment may interconnect the outer slide segment and the inner slide segment.
In some slide assemblies, a plurality of bearings may be interposed between the inner slide segment and the intermediate slide segment and between the intermediate slide segment and the outer slide segment. The bearings permit the slide segments to move relative to one another with very little resistance due to friction. As a result, the slide assembly is capable of supporting a relatively large load while remaining capable of extending and retracting with relatively little effort. However, in many common arrangements, the inclusion of bearings inhibits the ability to construct a three-segment slide assembly within a desirable cross-sectional envelope.
As a result, solid bearing slide assemblies are sometimes utilized for the computer server market. In a solid bearing, or friction, slide assembly, the individual slide segments are typically in direct contact with one another. However, in many prior art friction slides, such direct contact between the individual slide segments results in an excessive degree of resistance to extension or retraction due to relatively high friction between the slide segments. In addition, the height and/or position of the flat, horizontal contact surfaces may vary due to normal manufacturing tolerances such that an unacceptable amount of relative, vertical movement is permitted between the individual slide segments.
For example, a common over-travel, solid bearing slide assembly is illustrated in FIG. 1. The slide assembly 1 is a three-piece slide assembly having an inner slide segment 2, an intermediate slide segment 3 and an outer slide segment 4. The inner slide segment 2 is slideably engaged with the intermediate slide segment 3 which, in turn, is slideably engaged with the outer slide segment 4. The inner slide segment 2 defines substantially flat upper and lower contact surfaces 5, which contact substantially flat upper and lower contact surfaces 6 of the intermediate slide segment 3, respectively. Substantially flat upper and lower contact surfaces 7 of the intermediate slide segment 3 contact substantially flat upper and lower contact surfaces 8 of the outer slide segment 4.
The relatively large contact surface area between the individual slide segments 2, 3, 4, due to the substantially flat contact surfaces 5-8, results in a relatively large degree of friction when the slide segments 2, 3, 4 are moved with respect to one another. In addition, as described in greater detail below, the manufacturing process commonly used to form the slide segments 2, 3, 4 often results in an undesirable amount of vertical movement of the slide segments 2, 3, 4 relative to one another. Such undesirable relative motion is perceived by consumers as a looseness, or slop, of the slide assembly 1, which may cause concern regarding the adequacy of the support provided by the slide assembly 1 and result in a negative opinion regarding the quality of the slide assembly 1.
Accordingly, preferred embodiments of the present slide assembly are capable of supporting a 1U or 2U internet server and have a compact cross-sectional area, allowing the slide to sit within a 1xe2x80x3xc3x97xe2x85x9cxe2x80x3 cross-sectional envelope. Additionally, preferred embodiments of the present slide assembly are of a solid bearing construction wherein the individual slide segments include surfaces in direct contact with one another. Preferably, the contact surfaces are configured to have a relatively small surface area of the individual slide segments in contact with one another. Such an arrangement reduces the frictional, resistive force developed when the slide assembly is extended or retracted while supporting an object. Preferably, the contact surfaces are substantially continuously curved. In addition, the curved contact surfaces may be manufactured with conventional techniques to have a higher degree of dimensional precision and thereby reduce the amount of relative vertical movement between the individual slide segments in comparison to prior slide assemblies.
A preferred embodiment is a slide assembly including a first slide segment having a web, a first upper portion and a first lower portion spaced from one another along the web. The first upper portion defines a curved lower surface and the first lower portion defines an upper curved surface. A second slide segment is telescopingly engaged with the first slide segment and includes a web, a second upper portion and a second lower portion spaced from one another along the web. The second upper portion has a curved portion defining an innermost vertical surface, an outermost vertical surface and an upper curved surface extending from the innermost surface to the outermost surface. The second lower portion has a curved portion defining an innermost vertical surface, an outermost vertical surface and a lower curved surface extending between the innermost surface and the outermost surface. The lower curved surface of the first upper portion is configured to directly contact the upper curved surface of the second upper portion and the upper curved surface of the first lower portion is configured to directly contact the lower curved surface of the second lower portion.
Another preferred embodiment is a slide assembly including a first slide segment having a web, a first upper portion and a first lower portion spaced from one another along the web. The first upper portion defines a lower surface and the first lower portion defines an upper surface. A second slide segment is telescopingly engaged with the first slide segment and includes a web, a second upper portion and a second lower portion spaced from one another along the web. The second upper portion defines an innermost vertical surface, an outermost vertical surface and an upper surface extending from the innermost surface to the outermost surface. The second lower portion defines an innermost vertical surface, an outermost vertical surface and a lower surface extending between the innermost surface and the outermost surface. The upper surface of the second upper portion is configured to contact the lower surface of the first upper portion along an upper contact length of less than one-half of a distance between the innermost vertical surface and the outermost vertical surface of the second upper portion. Similarly, the lower surface of the second lower portion is configured to contact the upper surface of the first lower portion along a lower contact length of less than one-half of a distance between the innermost vertical surface and the outermost vertical surface of the second lower portion.
A further preferred embodiment is a slide assembly including a first slide segment having a web, a first upper portion and a first lower portion spaced from one another along the web. The first upper portion defines a continuously curved contact surface and the first lower portion defines a continuously curved contact surface. A second slide segment is telescopingly engaged with the first slide segment and includes a web, a second upper portion and a second lower portion spaced from one another along the web. A third slide segment includes a web, a third upper portion and a third lower portion spaced from one another along the web, the third upper portion defining a continuously curved contact surface and the third lower portion defining a continuously curved contact surface. A first curved surface of the second upper portion is in direct contact with a portion of the contact surface of the first upper portion and a first curved surface of the second lower portion is in direct contact with a portion of the contact surface of the first lower portion. Further, a second curved surface of the second upper portion is in direct contact with a portion of the contact surface of the third upper portion and a second curved surface of the second lower portion is in direct contact with a portion of the contact surface of the third lower portion.